This invention relates to suction inlet valves for fire truck pumpers. More particularly, this invention relates to suction inlet valves for fire truck pumpers useable in both hydrant and drafting operations.
Fire companies utilize pumper trucks to increase the pressure of hydrant water flowing through fire hoses and to pressurize water from drafting tanks. Pumpers draw water from sources, such as portable water tanks or fire hydrants, through suction valves.
Illustrative of a widely used suction inlet valve is the Pre-Con valve available from Hydra-Shield Manufacturing, Inc. of Irving, Tex., covered by U.S. Pat. No. 3,983,899. The Pre-Con valve is designed to operate as an automatic flow control valve which eliminates the need for manual adjustments in reaction to water flow. In hydrant operations, the Pre-Con valve automatically opens in proportion to the flow demand and is capable of automatically balancing flow between multiple water sources. The Pre-Con valve's automatic check valve action also minimizes water hammer. When drafting from a source of water, such as a portable water tank, the check valve action of the Pre-Con valve holds prime water when flow is stopped and allows switching to a booster tank and back to drafting without flow interruption. The Pre-Con valve has been used for some twenty years and is an improvement over butterfly valves which it has replaced in many situations.
The typical butterfly valve requires constant manual adjustment to adequately control flow and is subject to higher rates of valve wear requiring disassembly of the valves for maintenance. Moreover, butterfly valves have a relatively low maximum operating pressure of about 175 psi as opposed to a rating of 400 psi for the Pre-Con valves. Since the butterfly valves do not have automatic operation expensive remote controls are at times required to open and close the valves.
While the Pre-Con valves now in service are a vast improvement over butterfly valves, they are subject to corrosion and do not provide for manual as well as automatic operation.
In view of the aforementioned considerations, there is a need for a new and improved suction inlet valve for pumper fire trucks, which valve is less subject to corrosion and has automatic operation that can be manually adjusted if necessary or desired.